U.S. patent application number 13/201282 was filed with the patent office on 2011-12-01 for noise reducing grease composition.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Koji Hisaka, Shozo Ikejima, Kyosuke Ikuma, Mitsuhiro Kakizaki, Suehiro Okazaki, Koji Sakakibara.
Application Number | 20110294705 13/201282 |
Document ID | / |
Family ID | 42561880 |
Filed Date | 2011-12-01 |
United States Patent
Application |
20110294705 |
Kind Code |
A1 |
Ikuma; Kyosuke ; et
al. |
December 1, 2011 |
NOISE REDUCING GREASE COMPOSITION
Abstract
The invention provides a grease composition capable of smoothly
operating the lubricated parts even under wide-ranging temperature
conditions, and at the same time, exhibiting excellent noise
reducing effect on, the lubricated parts. The grease composition
containing a base oil and a thickener is provided, wherein the base
oil includes at least one first base oil selected from the group
consisting of poly-.alpha.-olefins and ethylene-.alpha.-olefin
oligomers and at least one second base oil selected from the group
consisting of polybutene, polyisobutylene, polymethacrylate, and
styrene based copolymers, with the first base oil being contained
in an amount of 65 mass % or more and the second base oil being
contained in an amount of 1 mass % or more and less than 35 mass %
based on the total mass of the base oil, the base oil having a
kinematic viscosity of 350 to 1400 mm.sup.2/s at 40.degree. C., the
first base oil having a kinematic viscosity of 300 to 1200
rnm.sup.2/s at 40.degree. C., and the second base oil having a
kinematic viscosity of 1500 to 200,000 mm.sup.2/s at 40.degree.
C.
Inventors: |
Ikuma; Kyosuke;
(Fujisawa-shi, JP) ; Kakizaki; Mitsuhiro;
(Fujisawa, JP) ; Sakakibara; Koji; (Kariya,
JP) ; Ikejima; Shozo; (Kariya, JP) ; Okazaki;
Suehiro; (Kariya, JP) ; Hisaka; Koji; (Kariya,
JP) |
Assignee: |
DENSO CORPORATION
Kariya
JP
KYODO YUSHI CO., LTD.
Fujisawa-shi
JP
|
Family ID: |
42561880 |
Appl. No.: |
13/201282 |
Filed: |
February 15, 2010 |
PCT Filed: |
February 15, 2010 |
PCT NO: |
PCT/JP2010/052188 |
371 Date: |
August 12, 2011 |
Current U.S.
Class: |
508/136 ;
508/110 |
Current CPC
Class: |
C10M 2209/0845 20130101;
C10M 2205/0265 20130101; C10M 2207/1285 20130101; C10M 2201/1056
20130101; C10M 2205/0285 20130101; C10M 107/02 20130101; C10N
2050/10 20130101; C10M 2215/223 20130101; C10N 2020/04 20130101;
C10M 2207/023 20130101; C10M 2219/068 20130101; C10N 2020/02
20130101; C10M 169/02 20130101; C10M 111/04 20130101; C10M 2205/043
20130101; C10N 2030/76 20200501; C10N 2020/06 20130101; C10M
2207/1285 20130101; C10N 2010/02 20130101; C10M 2219/068 20130101;
C10N 2010/12 20130101; C10M 2219/068 20130101; C10N 2010/12
20130101; C10M 2207/1285 20130101; C10N 2010/02 20130101 |
Class at
Publication: |
508/136 ;
508/110 |
International
Class: |
C10M 169/02 20060101
C10M169/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 13, 2009 |
JP |
2009-031496 |
Claims
1. A grease composition comprising a base oil and a thickener,
wherein the base oil comprises at least one first base oil selected
from the group consisting of poly-.alpha.-olefins and
ethylene-.alpha.-olefin oligomers and at least one second base oil
selected from the group consisting of polybutene, polyisobutylene,
polymethacrylate, and styrene based copolymers, the content of the
first base oil exceeds 65 mass % and the content of the second base
oil is 1 mass % or more and less than 35 mass %, with respect to
the total mass of the base oil, the base oil has a kinematic
viscosity of 350 to 1400 mm.sup.2/s at 40.degree. C., the first
base oil has a kinematic viscosity of 300 to 1200 mm/s at
40.degree. C., and the second base oil has a kinematic viscosity of
1500 to 200,000 mm.sup.2/s at 40.degree. C.
2. The grease composition of claim 1, wherein the second base oil
comprises the polybutene.
3. The grease composition of claim 1, wherein the thickener
comprises silica.
4. The grease composition of claim 1, wherein the olybutene has a
number-average molecular weight of 600 to 4000.
5. An air conditioning unit for vehicles, comprising the grease
composition of claim 1.
6. The grease composition of claim 2, wherein the thickener
comprises silica.
7. The grease composition of claim 2, wherein the olybutene has a
number-average molecular weight of 600 to 4000.
8. The grease composition of claim 3, wherein the olybutene has a
number-average molecular weight of 600 to 4000.
9. The grease composition of claim 6, wherein the olybutene has a
number-average molecular weight of 600 to 4000.
Description
TECHNICAL FIELD
[0001] The present invention relates to a grease composition having
excellent noise reduction effect and operability at low
temperatures.
BACKGROUND ART
[0002] The recent upgrading of cars has requested to enhance the
quality of each automotive part. Noise reduction of the automotive
parts has become one of the problems to be solved. There is also a
demand for improvement of the grease performnce to reduce the noise
of automotive parts. As for the grease performance, there is
another demand for the temperature properties covering a wider
range (from high temperatures to low temperatures).
[0003] Addition of a polymer, which is a measure taken to reduce
noise has achieved the goal to some extent. For example, there is
disclosed a grease composition provided with noise reduction
performance by adding a ultra-high molecular weight polyolefin
powder (Japanese Patent Unexamined Publication (JP Kokai) Hei
07-173483).
[0004] However, the base oils and polymers with high viscosities
are inferior in fluidity at low temperatures (due to their high
pour points), so that the operating temperature region will be
limited. Accordingly, both properties may not be satisfied
according to the selection of base oils and polymers.
[0005] Further, the grease where the polymer powders are added as
mentioned above has the drawback of short life because the grease
may be hardened upon heating.
SUMMARY OF INVENTION
Technical Problem
[0006] An object of the invention is to provide a grease
composition capable of smoothly operating the lubricated parts
under the wide-ranging temperature conditions.
[0007] Another object of the invention is to provide a grease
composition having excellent noise reducing effect on the
lubricated parts.
[0008] It is a further object of the invention to provide a grease
composition having excellent noise reduction effect while
maintaining satisfactory operability at low temperatures.
[0009] It is a still another object of the invention to provide a
unit where the above-mentioned grease composition is packed for
lubrication, in particular, an air conditioning unit for
vehicles.
Solution to Problem
[0010] The inventors of the present invention found that when a
predetermined amount of a second base oil with a high viscosity is
added to a first base oil with a low viscosity, noise reduction of
the lubricated parts can be improved, with good operability at low
temperatures being maintained. The invention has been thus
accomplished based on the above findings. The invention provides a
grease composition and a unit where the grease composition is
packed for lubrication, as shown below.
[0011] (1) A grease composition comprising a base oil and a
thickener, wherein the base oil comprises at least one first base
oil selected from the group consisting of poly-.alpha.-olefins and
ethylene-.alpha.-olefin ohgomers and at least one second base oil
selected from the group consisting of polybutene, polyisobutylene,
polymethacrylate, and styrene based copolymers,
[0012] the content of the first base oil exceeds 65 mass % and the
content of the second base oil is 1 mass % or more and less than 35
mass %, with respect to the total mass of the base oil,
[0013] the base oil has a kinematic viscosity of 350 to 1400
mm.sup.2/s at 40.degree. C.,
[0014] the first base oil has a kinematic viscosity of 300 to 1200
mm.sup.2/s at 40.degree. C. and
[0015] the second base oil has a kinematic viscosity of 1500 to
200,000 mm.sup.2/s at 40.degree. C.
[0016] (2) The noise reducing grease composition described in the
above-mentioned item (1), characterized in that the second base oil
comprises polybutene.
[0017] (3) The noise reducing grease composition described in the
above-mentioned item (1) or (2), wherein the thickener comprises
silica.
[0018] (4) The noise reducing grease composition described in any
one of the above-mentioned items (1) to (3), wherein the polybutene
has a number-average molecular weight of 600 to 4000.
[0019] (5) An air conditioning unit for vehicles, comprising the
noise reducing grease composition described in any one of the
above-mentioned items (1) to (4).
ADVANTAGEOUS EFFECTS OF INVENTION
[0020] The grease composition of the invention is excellent in
operability at low temperatures and also excellent in noise
reducing effect on the units lubricated with the grease
composition, in particular, an air conditioning unit or the like
for use in vehicles.
DESCRIPTION OF EMBODIMENTS
[0021] The thickener used in the grease composition of the
invention is not particularly limited, but any thickeners are
available. For example, there can be used soap-based thickeners
including Li soap and Li complex soap; urea thickeners including
diurea; inorganic thickeners such as organoclay and silica; organic
thickeners including PTFE, and the like. Particularly preferred is
silica, which is a thickener excellent in noise reduction
performance and operability at low temperatures. The silica may
preferably have an average particle diameter of 0.1 .mu.m or less,
more preferably 0.05 .mu.m or less.
[0022] The amount of thickener to be added is not particularly
limited so long as a desired consistency can be obtained.
Generally, the amount of thickener may be preferably in the range
of 3 to 20 mass %, and more preferably 5 to 15 mass %, based on the
total mass of the grease composition.
[0023] The base oil used for the grease composition according to
the invention comprises at least one first base oil selected from
the group consisting of poly-.alpha.-olefins and
ethylene-.alpha.-olefin oligomers and at least one second base oil
selected from the group consisting of polybutene, polyisobutylene,
polymethacrylate, and styrene based copolymers.
[0024] The content of the first base oil exceeds 65 mass %,
preferably 90 mass % or more, and the content of the second base
oil is 1 mass % or more and less than 35 mass %, preferably in the
range of 1 to 10 mass %, with respect to the total mass of the base
oil.
[0025] The base oil has a kinematic viscosity of 350 to 1400
mm.sup.2/s, preferably 400 to 600 mm.sup.2/s at 40.degree. C.
[0026] The first base oil has a kinematic viscosity of 300 to 1200
mm.sup.2/s, preferably 350 to 550 mm.sup.2/s at 40.degree. C.
[0027] The second base oil has a kinematic viscosity of 1500 to
200,000 mm.sup.2/s, preferably 2000 to 180,000 mm.sup.2/s at
40.degree. C.
[0028] Any of the poly-.alpha.-olefins and ethylene-.alpha.-olefin
oligomers that can be used as the first base oil show excellent
operability at low temperatures.
[0029] Among polybutene, polyisobutylene, polymethacrylate and
styrene based copolymers that can be used as the second base oil,
polybutene is particularly preferred.
[0030] The pressure-viscosity coefficient (.alpha.) of the first
base oil may preferably be 10 to 20 GPa.sup.-1, and the
pressure-viscosity coefficient (.alpha.) of the second base oil may
preferably be 25 GPa.sup.-1 or more.
[0031] The second base oil can exhibit excellent noise reduction
effect on the ground of high pressure-viscosity coefficient
(.alpha.). Especially, polybutene can exhibit excellent noise
reduction effect because the pressure-viscosity coefficient
(.alpha.) is as high as about 30 GPa.sup.-1 (Masayoshi Muraki:
Viscosity-pressure properties, Junkatsu, vol. 33, 1 (1988) p.
36).
[0032] Preferably, the second base oil, specifically, polybutene
may have a number-average molecular weight of 600 to 4000, more
preferably 750 to 3000. It is necessary to adjust the amount of the
second base oil, particularly polybutene when added because the
operability at low temperatures is not satisfactory.
[0033] The second base oil is contained in an amount of 1 mass % or
more and less than 35 mass %, preferably 1 to 30 mass %, and more
preferably 2 to 10 mass %, with respect to the total mass of the
base oil.
[0034] The base oil used in the invention may further comprise a
third base oil other than the above-mentioned first and second base
oils. Examples of the third base oil include ester based synthetic
oils such as esters, diesters and polyol esters; ether based
synthetic oils such as alkyl diphenyl ethers and polypropylene
glycol; silicone oils; fluorine-containing oils, and the like. The
content of the third base oil may preferably be 5 mass % or less,
more preferably 1 mass % or less, with respect to the total mass of
the base oil. However, it is most preferable not to add the third
base oil.
[0035] The kinematic viscosity of the base oil is 350 to 1400
mm.sup.2/s, preferably 500 to 1000 mm.sup.2/s at 40.degree. C. With
the kinematic viscosity of less than 350 mm.sup.2/s, a desired
noise reduction effect cannot be obtained. When the kinematic
viscosity is more than 1400 mm.sup.2/s, the operability at low
temperatures tends to worsen.
[0036] The grease composition of the invention may further comprise
a variety of additives when necessary. For example, antioxidants
including phenols and amines; rust preventives including calcium
sulfonate; metal corrosion inhibitors such as benzotriazole;
oiliness improvers such as castor oil; extreme pressure agents
including molybdenum dithiocarbamate and zinc dithiophosphate;
solid lubricants including PTFE and MCA, and the like can be
used.
[0037] As a noise-reduction measure, it is effective to increase
the kinematic viscosity by the addition of polymers, as previously
mentioned. It is considered that both the noise reduction
performance and the operability at low temperatures can be
satisfied by adding a small amount of the second base oil such as
polybutene or the like which has a high molecular weight and a high
pressure-viscosity coefficient (.alpha.), with the balance between
noise reduction performance and the operability at low temperatures
being taken into account.
Examples 1 to 6 and Comparative Examples 1 to 6
[0038] Sample greases were prepared in accordance with the
formulations shown in Thbles 1 and 2.
[0039] Two kinds of thickeners, i.e., silica (with an average
particle diameter of 0.012 .mu.m) and Li soap (Li-(12OH)St) were
used.
[0040] With respect to the base oil, poly .alpha.-olefins (A and B)
and ethylene-.alpha.-olefin oligomer were used as the first base
oil; and polybutenes (A to C) were used as the second base oil.
Their respective kinematic viscosities at 40.degree. C. are shown
below. The pressure-viscosity coefficients (.alpha.) of polybutene
A and polybutene B used as the second base oil are 25 GPa.sup.-1 or
more; while the pressure-viscosity coefficient (.alpha.) of
polybutene C is less than 25 GPa.sup.-1.
[0041] The content of the base oil in total is obtained by
subtracting the total mass of the thickener and other additives
from the total mass of the grease composition. The numerical values
shown in the columns of the first base oil and the second base oil
indicate "mass %" based on the total mass of the both base
oils.
First Base Oil
[0042] poly-.alpha.-olefin A (of comparative example): 30.5
mm.sup.2/s
[0043] poly-.alpha.-olefin B (of the invention):
poly-.alpha.-olefin: 390 mm.sup.2/s
[0044] ethylene-.alpha.-olefin oligomer C (of the invention): 380
mm.sup.2/s
Second Base Oil
[0045] polybutene A (of invention): 160,000 mm.sup.2/s
(number-average molecular weight: 2900)
[0046] polybutene B (of invention): 2300 mm.sup.2/s (number-average
molecular weight: 750)
[0047] polybutene C (of comparative example): 205 mm.sup.2/s
(number-average molecular weight: 500)
[0048] Extreme pressure agent: molybdenum dithiocarbam.ate (1.5
mass % based on the total mass of grease)
[0049] Rust preventive: benzotriazole (0.05 mass % based on the
total mass of grease
[0050] Antioxidant: phenol (1.0 mass % based on the total mass of
grease)
Worked Penetration (JIS K2220 7.)
[0051] The worked penetration was adjusted to 280 or 300.
Steel Ball Drop Test (Test for Evaluating the Noise Reduction
Effect)
[0052] To evaluate the noise reduction effect, each grease was
applied to the surface of a steel plate shown below. By dropping
the steel ball from a predetermined height, the sound pressure was
determined. The sound pressure level of less than 89.6 dB was
evaluated as acceptable (marked with "o").
(Test Conditions)
[0053] Thickness of applied grease: 0.5 mm
[0054] Area of applied grease: 2500 mm.sup.2
[0055] Size of steel plate: 200 mm.times.150 mm.times.1.6 mm
[0056] Position of microphone: 200 mm above from steel plate
[0057] Original position of steel ball: 100 min above from steel
plate
[0058] Diameter of steel ball: 12.7 mm
[0059] Measuring instrument: 2-channel hand-held FFT analyzer, made
by RION Co., Ltd.
Low Temperature Torque Test (HS K2220 18.)
[0060] When the starting torque of less than 380 mNm and the
running torque of less than 320 mNm under the conditions of
-30.degree. C., the grease was evaluated as acceptable (marked with
"o").
[0061] When compared with the comparative examples, significant
improvements in the sound pressure levels (of less than 89.6 dB)
and the low temperature torques (i.e., the starting torques of less
than 380 mNm and the running torques of less than 320 mNm) can be
recognized in the grease compositions of Examples 1 and 2 where the
poly-.alpha.-olefin B with a kinematic viscosity of 390 mm.sup.2/s
at 40.degree. C. was used as the first base oil and the polybutene
A with a kinematic viscosity of 160,000 mm.sup.2/s at 40.degree. C.
was added in an amount of 5 and 7%; the grease composition of
Example 3 where the polybutene B with a kinematic viscosity of 2300
mm.sup.2/s at 40.degree. C. was added in an amount of 32%; the
grease composition of Example 4 where the worked penetration as in
Example 1 was adjusted to 300; the grease composition of Example 5
where the ethylene-.alpha.-olefin oligomer C with a kinematic
viscosity of 380 mm.sup.2/s at 40.degree. C. was used as the first
base oil and the polybutene A with a kinematic viscosity of 160,000
mm.sup.2/s at 40.degree. C. was added in an amount of 5%; and the
grease composition of Example 6 where silica used as the thickener
in Example 1 was replaced by Li soap.
[0062] In Comparative Example 1, the first base oil as used in
Example 1 was used alone for the base oil. The results are that the
kinematic viscosity of the base oil becomes lower as a whole,
thereby degrading the noise reduction performance although the
operability at low temperatures is satisfactory,
[0063] In Comparative Example 2, the amount of the second base oil
as used in Example 3 was increased from 32 mass % to 35 mass %. The
results are that the operability at low temperatures is inferior
although the noise reduction performance is satisfactory.
[0064] In Comparative Example 3, the amount of the second base oil
as used in Example 1 was increased from 5 mass % to 32 mass % and
the kinematic viscosity of the base oil was 1500 mm.sup.2/s. The
results are that the operability at low temperatures is inferior
although the noise reduction performance is satisfactory.
[0065] In Comparative Example 4, the poly-.alpha.-olefin B with a
kinematic viscosity of 390 rnm.sup.2/s at 40.degree. C. as used in
Comparative Example 3 was replaced by the poly-.alpha.-olefin A
with a kinematic viscosity of 30.5 mm.sup.2/s at 40.degree. C. as
the first base oil. The results are that the kinematic viscosity of
the base oil is lowered as a whole, thereby degrading the noise
reduction performance although the operability at low temperatures
is satisfactory.
[0066] Unlike Example 1, Comparative Example 5 used the polybutene
C with a kinematic viscosity of 205 mm.sup.2/s at 40.degree. C. in
an amount of 15%. The results are that the kinematic viscosity of
the base oil is lowered as a whole, thereby degrading the noise
reduction performance although the operability at low temperatures
is satisfactory.
[0067] Unlike Comparative Example 1, Comparative Example 6 used the
first base oil of the polybutene C with a kinematic viscosity of
205 mrn.sup.2/s at 40.degree. C. alone. The results are that the
kinematic viscosity of the base oil is increased as a whole,
thereby degrading the operability at low temperatures although the
noise reduction performance is satisfactory.
TABLE-US-00001 TABLE 1 Examples 1 2 3 4 5 6 Thickener silica silica
silica silica silica Li soap Amount (mass %) 11.0 10.5 11.0 10.5
11.0 7.5 First base oil A B 95.0 93.0 68.0 95.0 95.0 C 95.0 Second
base oil A 5.0 7.0 5.0 5.0 5.0 B 32.0 C Kinematic viscosity 518 576
558 518 525 518 of base oil Worked penetration 280 280 280 300 280
280 Steel ball drop test 87.2 87.4 86.8 88.6 88.7 88 Evaluation
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. Low temperature torque test Starting
torque 250 240 320 200 230 230 Running torque 200 200 280 180 220
180 Evaluation .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle.
TABLE-US-00002 TABLE 2 Comparative Examples 1 2 3 4 5 6 Thickener
silica silica silica silica silica silica Amount (mass %) 12.0 11.0
6.0 12.0 12.0 7.0 First base oil A 68.0 B 100.0 65.0 68.0 85.0 C
100.0 Second base oil A 32.0 32.0 B 35.0 C 15.0 Kinematic viscosity
390 583 1500 360 355 1240 of base oil Worked penetration 280 280
280 280 280 280 Steel ball drop test 89.6 86.8 85.6 89.7 90 85.5
Evaluation x .smallcircle. .smallcircle. x x .smallcircle. Low
temperature torque test Starting torque 180 390 480 200 190 1150
Running torque 160 360 430 170 160 860 Evaluation .smallcircle. x x
.smallcircle. .smallcircle. x
* * * * *